Y-Shaped support for piezoelectric resonator

ABSTRACT

A quartz unit is arranged to permit its automatic manufacture of it. The quartz unit includes a quartz vibrator; a pair of opposed terminal metal fittings each consisting of a stem part, branch parts protruding from one end of the stem part on two sides thereof to form a Y shape and support parts protruding from the fore ends of the branch parts to carry jointly the quartz vibrator; electrodes of the quartz vibrator connected to the terminal metal fittings through the support parts; and a container consisting of front and rear halves which are joined together to effect sealing with the metal fittings interposed in between them. The stem, branch and support parts are obtained by punching from a metal plate in one unified body.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method of manufacturing a quartz unit inwhich assembly work and even the fine adjustment of frequency arecarried out automatically.

2. Description of the Prior Art

Heretofore, the quartz vibrator of a quartz unit, particularly in thecase of a quartz unit of the AT or BT cut type, has been arranged to becarried by wire clips or ribbon clips. Referring to the accompanyingdrawings, FIG. 1(a) shows an example of the quartz unit using wire clipswhile FIG. 1(b) shows an enlarged view thereof. Each support member 2has its fore end formed into a coil shaped clip 1. The quartz vibrator 3is carried by these support members 2 with its periphery pinched bythese clips 1. The ribbon clip arrangement is also similar to this.These conventional quartz vibrator supporting arrangements havenecessitated entrusting the most part of the assembly work to the manualwork of skilled workers.

The heavy reliance on the manual assembly work on the quartz vibratorhas inevitably resulted in some deformation of the support members.Correction of such deformation then has resulted in a mechanicalresidual stress which in turn has affected the quartz vibrator to resultinevitably in some detriment of the properties of the quartz vibrator.The conventional arrangements thus have been lacking uniform workabilityrequired for obtaining a quartz unit of high precision.

SUMMARY OF THE INVENTION

It is therefore a general object of the present invention to provide aquartz unit which is arranged to permit automation of the assembly work,frequency adjustment and even test work on the quartz units by means ofrobots without having recourse to the skill of workers.

The above and further objects, features and advantages of the inventionwill become apparent from the following detailed description of thepreferred embodiments thereof taken in connection with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(a) and 1(b) are a front view and an enlarged view thereofshowing the conventional quartz unit of the wire clip type.

FIGS. 2(a) and 2(b) are a plan view and a front view respectivelyshowing a quartz unit as an embodiment of the invention.

FIGS. 3(a) and 3(b) are a plan view and a side view respectively showingthe original shape of a metal piece to be formed into a terminal metalfitting.

FIGS. 4(a) and 4(b) are a plan view and a side view respectively showingthe metal piece as halfway in a process of being bent.

FIGS. 5(a) and 5(b) are a plan view and a side view showing the terminalmetal fitting obtained from the metal piece by further bending thebranch parts of the metal piece into a Y shape.

FIGS. 6(a) and 6(b) are plan view and a side view respectively showing aquartz vibrator as in a state of being mounted on a pair of opposedterminal metal fittings.

FIG. 7 is a sectional view of the quartz unit as in a state of havingbeen completed by covering and sealing it with a container from frontand rear sides thereof.

FIG. 8 is a plan view showing a frame consisting of a ribbon like metalpiece obtained by punching as the original shape of terminal metalfittings.

FIG. 9 is a plan view showing the terminal metal fittings as in a stateof having been formed by bending the original shape of the frame.

FIG. 10 is a plan view showing the frame as in a state of having beencovered with a half part of a container from the rear.

FIGS. 11(a) and 11(b) are a plan view and a perspective view showing theframe as in a state of having a quartz vibrator mounted thereof.

FIG. 12 is a schematic plan view showing a partial vacuum evaporationprocess.

FIG. 13 is a plan view showing a quartz vibrator having silver appliedthereto by partial plating.

FIGS. 14 and 15 are plan views respectively showing terminal metalfittings as other embodiment examples.

FIGS. 16(a) and 16(b) are a plan view and a perspective view,respectively showing a further embodiment, FIG. 16(a) showing a quartzunit provided with terminal metal fittings and FIG. 16(b) showing thebent state of the terminal metal fittings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 2(a) and 2(b) show an example of applying the invention to aquartz unit. A quartz vibrator 5 which is shown with a broken line iscarried by terminal metal fittings 6a and 6b and is covered from frontand rear with container halves 7a and 7b which are made of an insulatingmaterial such as glass. The peripheral portions 7-1 of the containerhalves 7a and 7b are provided with a coating. The terminal metalfittings 6a and 6b are interposed in between these peripheral portions7-1 and airtightly sealed by pressure joining and heating together withthe terminal metal fittings 6a and 6b.

Drawings from FIG. 3 through FIG. 5 show the details of the above-statedterminal metal fittings 6a and 6b. A thin metal piece 6 shaped as shownin FIG. 3(a) is bent into a stem part 6-1, branch parts 6-2 and supportparts 6-3 as shown in FIGS. 4(a) and 4(b). Then, the branch parts 6-2are further bent into a Y shape relative to the stem part 6-1 to obtainthe terminal metal fitting 6a or 6b as shown in a plan view and a sideview in FIGS. 5(a) and 5(b).

In assembling, the terminal metal fittings 6a and 6b are set opposite toeach other in horizontal positions as shown in FIGS. 6(a) and 6(b). Onthese terminal metal fittings, is mounted the quartz vibrator 5 to becarried by the support parts 6-3 of the terminal metal fittings. In thisinstance, it is essential to have the lead-out parts 5-1a of the frontand back electrodes 5-1 of the quartz vibrator 5 in contact with atleast one of the two support parts 6-3 of each terminal metal fitting 6aor 6b.

With the quartz vibrator 5 thus mounted, a conductive coating materialis dropped onto each of the support parts. The coating material is thenheated and allowed to harden. The quartz vibrator 5 is thus secured tothe support parts and is carried thereby with sufficient mechanicalstrength. Meanwhile, the electrodes 5-1 on the front side and the backside are connected respectively to the terminal metal fittings 6a and6b.

After that, the quartz vibrator is covered with container halves orcontainers 7a and 7b from front and rear as shown in FIG. 7. The innersurfaces 7-1 of the containers 7a and 7b in the periphery portions ofthem have been provided with some coating beforehand respectively. Thecontainers are then joined together by softening the coating withheating by means of an infrared ray or the like and then by allowing thecoating to harden. With the coating thus hardened a quartz unit 8 isobtained in an airtight sealed state.

Since the quartz vibrator 5 is carried by the support parts 6-3 formedat the fore ends of the branch parts of the terminal metal fittingswhich are bent into the Y shape, the quartz vibrator 5 is in a state ofbeing carried by a highly flexible material, so that the quartz unit ismade to have extremely stable characteristics. Further, the structuralarrangement as shown in FIG. 6 can be arranged for quartz vibrator ofdifferent sizes. In other words, the bending angle of the branch parts6-2 of each terminal metal fittings 6a or 6b relative to the stem partcan be adjusted to obtain a Y shape that is most suited to the quartzvibrator to be used.

Further, the material and the thickness of the metal piece to be usedfor forming the terminal metal fittings 6a and 6b and the width, length,etc. of the stem and branch parts of them must be selected not to affectthe properties of the quartz vibrator 5. They can be prepared withoutdifficulty by ordinary thin metal plate processing technique includingpress punching, etching, etc.

The assembly work on the quartz unit of the construction described abovecan be automated by continuously arranging many terminal metal fittingsin the following manner: One example of this is as shown in FIG. 8. Inthis case, many terminal metal fittings 6 of the shape as shown in FIG.3 are formed on a thin strip of metal by a suitable process such aspunching or the like to obtain the frame 9. The frame 9 is provided withperforation or guide holes 10 which are formed in the peripheral portionof the frame. The guide holes 10 permit automatic feeding for furtherprocesses.

More specifically stated, two terminal metal fittings 6 are formed ineach section of the frame 9 and are disposed in the upper and lowerpositions in each section. In other words, the terminal metal fittings 6are arranged to have one quartz unit at every section. Then, each of theterminal metal fittings is subjected to the bending process which iscarried out as shown in FIGS. 3, 4 and 5 to obtain terminal metalfittings 6a and 6b having their fore ends formed into a Y shape as shownin FIG. 9. Meanwhile, one (7b) of the container halves 7a and 7b isprepared to have a predetermined inner part of the peripheral portionthereof coated with low melting point glass or the like beforehand. Thecontainer half 7b thus prepared is applied and secured to the rear sidesof the opposed pair of terminal metal fittings 6a and 6b formed in eachsection as shown in FIG. 10.

The reason for securing one of the container halves to both the terminalmetal fittings as described above resides in that: At the time ofcarrying out a partial vacuum evaporation process which will bedescribed later herein, one (6a) of the pair of terminal metal fittingsis cut off from the frame for the purpose of allowing the quartz unit tooscillate. With the metal fitting 6a thus cut off, the quartz vibrator 5has to be carried solely by the other metal fitting 6b. If the containerhalf is not arranged beforehand in the manner as described above, anexcessive stress would be applied to the branch part 6-2 of the terminalmetal fitting 6b and to the point at which the quartz vibrator 5 issupported. To solve this problem, one of the container halves is fixedlyattached beforehand to both the pair of terminal metal fittings 6a and6b as described above. This arrangement is of course unnecessary wherethe quartz vibrator is sufficiently supportable by the terminal metalfitting 6b alone. In such a case, both the front and rear containerhalves 7a and 7b can be mounted later at the time of the final processof sealing.

Referring now to FIG. 11(a), with the frame 9 horizontally set, a quartzvibrator 5 which has been sucked by an air chuck provided on the tip ofa robot's arm (not shown) is laid on every section as shown in FIGS.6(a) and 6(b) to be carried by the support parts 6-3 of the terminalmetal fittings 6a and 6b. Following this, a conductive coating materialis dropped onto each support part of the terminal metal fittings by asuitable constant delivery means. The coating material thus dropped isheated and hardened.

In laying the quartz vibrator on each section of the frame, the quartzvibrator must be so oriented as to have the lead-out parts 5-1a of theelectrodes come into contact with at least one of the support parts 6-3of the terminal metal fittings. However, in attaching the electrodes 5-1to the quartz vibrator by vacuum evaporation, the evaporation process iscarried out by determining the direction of the electrode lead-out part5-1a. Therefore, at the time of laying the quartz vibrator on the frame,the labor required in judging the direction of the quartz vibrator canbe saved by utilizing the direction thereof determined at the time ofattaching the electrode. Again referring to FIG. 11, one 6a of theterminal metal fittings is cut at a part A as shown by a broken line.With the terminal metal fitting 6a cut off in that manner, the quartzunit of each section of the frame 9 becomes an independent quartz unitconnected through the other terminal metal fitting 6b to other quartzunits. Following that, fine adjustment of frequency is carried out by apartial vacuum evaporation process.

This partial evaporation process is carried out in a manner as shown inFIG. 12. The arrangement for this process includes a vacuum tank 11; avapor generator 12 which is arranged to generate the vapor of anevaporating material such as silver (Ag) by heating the material; ashutter 13; and a mask 14. First, the frame 9 which has a quartzvibrator mounted on every section thereof as shown in FIG. 11(a) ismounted in an arcuate manner on a mounting base with a small hole 12a ofthe vapor generator 12 located at the center of the frame.

FIG. 11(b) shows a modification in which the IC type terminal metalfittings (frame) is provided with four terminals, and either of theterminals 6a and 6b is cut off from the frame 9, so that a plurality ofquartz vibrators arranged on the terminal metal fittings can producetheir own functions just as in the embodiment shown in FIG. 11(a) inwhich the terminal 60 is cut off at the portion A.

The above procedure is necessary for checking the resonance frequency orcrystal impedance in the subsequent step.

The vapor of silver which is employed as evaporating material isarranged to be jetted out of the small hole 12a of the vapor generator12. This vapor is normally blocked by the shutter 13. In carrying outfrequency adjustment, each quartz vibrator 5 set in a predeterminedposition is connected to an external oscillation circuit 16 through acontactor 15 thus to form a quartz unit. Meanwhile, there is provided amonitor 17 which is arranged to monitor deviation of the frequency f ofthe oscillation of the quartz vibrator from a preset referencefrequency.

The thickness of the quartz vibrator 5 is coarsely adjusted prior to theabove-stated assembly work in such a way as to have the frequencythereof at a value a slightly higher than a prescribed frequency. At thetime of the fine adjustment, the shutter 13 is opened to allow thesilver vapor jetted out of the small hole 12a to be applied through themask 14 onto the electrode 5-1 of the quartz vibrator 5 as representedby a part 5-2 in FIG. 13. The quantity of silver applied to the part 5-2increases with time. The oscillation frequency decreases according asthe silver quantity increases. When the monitor 17 detects that theoscillation frequency has reached the prescribed value, the shutter 13is closed and the frame 9 is moved forward in the direction of arrow 18to the extent of one section thereof to have next quartz vibrator in theposition for the vacuum evaporation process. The quartz units indifferent sections of the frame 9 are thus adjusted to a prescribedfrequency one after another.

After the fine adjustment of frequency, the quartz vibrator and theterminal metal fittings of every section is covered with a front half 7aof the insulating container which has been provided with a coating onthe inner side of the peripheral portion 7-1 thereof. This coveringprocess is carried out in a suitable atmosphere such as dry nitrogen gas(N₂) and is completed by heating and hardening the coating to obtainquartz units with the nitrogen gas tightly sealed within the container.Upon completion of this sealing process, the part B shown in FIG. 11(a)is cut off at each section of the frame to obtain individual quartzunits.

In accordance with the method of the present invention as has beendescribed in the foregoing, many frame sections are continuouslyarranged on a strip of metal sheet material with terminal metal fittingsarranged to form an oscillator within each of these sections. This isfollowed by a sequence of steps of mounting the rear half of thecontainer, laying each quartz vibrator in place, cutting one of the pairof terminal metal fittings, carrying out fine adjustment of frequency bya partial vacuum evaporation process, mounting of the front half of thecontainer in a prescribed atmosphere and finally cutting off the otherterminal metal fitting on the common side of the frame to obtainindividual quartz units. All these steps can be automated withoutdifficulty. This automation permits manufacture of quartz units ofuniform characteristics without having recourse to the skill of workers.

In the embodiment described in the foregoing, the quartz vibrator isarranged to be supported at four points by the support parts two ofwhich are provided on each of the pair of terminal metal fittings. Inanother embodiment, this supporting arrangement is replaced witharrangement to support it with three support parts in a manner asdescribed below:

In this embodiment, the pair of terminal metal fittings shown in FIG. 8is not formed into the same shape. One of them is modified to have onlyone support part instead of two. The quartz vibrator in this case isthus supported at three points instead of four. Further, the quartzvibrator is not limited to a circular shape but may be formed into anyother shapes such as a rectangular shape, etc.

FIG. 14 shows a further modification of the terminal metal fittingsshown in FIG. 8. In this case, there are provided notches in the rootparts 6-1a and 6-1b and parts 6-3a and 6-3b between the branch parts andthe support parts as shown in FIG. 14. The provision of these notchesfacilitate the bending work on the terminal metal fittings for shapingthem as shown in FIG. 5.

FIG. 15 shows a still further embodiment of the invention. In this case,the stem part 6-1 of the terminal metal fitting 6 is formed to have awidth D for a portion a thereof continuing to the branch part 6-2 and tohave a much narrower width d for a portion b leading to the frame. Thequartz unit 8 formed in this manner has the portion b of the stem part6-1 serve as lead wire for mounting on a printed circuit board as shownFIG. 16(a). In mounting the quartz unit 8 on a printed circuit board,the lead wire-like portions of the terminal metal fittings of the quartzunit are bent as shown in FIG. 16(b). The quartz unit 8 then can bereadily mounted in place by inserting the bent lead wire-like portionsinto mounting holes.

Further, the container halves 7a and 7b may be arranged to have thequartz vibrator set closer to one of the container halves, for example,closer to the container half 7b, by bending the terminal metal fittings6a and 6b into a suitable shape as shown in FIG. 7. This arrangementthen permits the other half 7a of the container to be formed merely intoa shape of plate-like lid.

As described in the foregoing, the invention permits automation of allassembly work, fine adjustment of frequency, etc. to facilitatemanufacture of many quartz units of uniform characteristics.

What is claimed is:
 1. A quartz unit comprising:a quartz vibrator; apair of opposed Y-shaped terminal metal fittings,each including a stempart having a first end and a second end, a pair of branch parts eachprotruding angularly from said first end of said stem and beingangularly spaced relative to one another, and a support part for saidquartz vibrator located at the end of each said branch parts spaced fromsaid stem part and said support parts protruding in a directiongenerally opposite to the direction of said stem part from the first endto the second end thereof, said support parts on each said terminalmetal fitting confronting in spaced relation said support parts on theother said terminal metal fitting, and said support parts being bentrelative to said branch parts and arranged to carry the quartz vibratorwith said support parts located in a common plane; said quartz vibratorhaving a pair of electrodes with each said electrode connected to adifferent one of said terminal metal fittings through one of saidsupport parts thereon; and a container comprising a front and a rearpart enclosing and supporting said terminal metal fittings with saidfront and rear parts joined together and sealed in an airtight manner.2. A quartz unit acccording to claim 1, wherein said stem part, branchparts and support parts of each said terminal metal fitting are formedinto one unified body obtained by punching from a metal plate.
 3. Aquartz unit according to claim 1, wherein said container parts areformed of an insulating material.
 4. A quartz unit according to claim 3,wherein said container parts are formed of glass.
 5. A quartz unitaccording to claim 1, wherein said container parts have a rectangularpan-like shape.
 6. A quartz unit according to claim 1, wherein saidquartz vibrator is bonded to said support parts.
 7. A quartz unitaccording to claim 1, wherein the contacting surfaces of said containerparts are coated with a softenable material so that the softenablematerial can be heated and then allowed to harden after the containerparts have been placed in contacting engagement.
 8. A quartz unitaccording to claim 1, wherein nitrogen gas is introduced into saidcontainer so that in the sealed airtight condition a nitrogen gasatmosphere is present within said container.
 9. A quartz unit accordingto claim 1, wherein said stem has a first part extending from saidbranch parts and a second part extending from said first part remotefrom said stem parts, said first part having a greater width than saidsecond part, and said second part serves as a lead wire for mounting thequartz unit on a printed circuit board.